1. Field of the Invention
The present invention relates to an improvement in a rocker switch that is used in various kinds of OA (office automation) machines or equipments, amusement and game machines, measurement instruments, medical instruments and the like.
2. Description of the Related Art
A rocker switch (also called a seesaw switch due to its mechanism) is used, for example, as a power switch in various kinds of OA machines, amusement and game machines, measurement instruments, medical instruments and the like. In general, the rocker switch is constructed such that its switch components or parts are housed in a square or rectangular box (casing) the top of which is open and an operation button (operation knob) is mounted at the opening space of the box at the top thereof such that it can be moved for seesaw movement.
Various types of rocker switches having their constructions or structures different from one another have been heretofore proposed, and the present invention relates to an improvement in a rocker switch of the type in which a movable contact piece is made of an elastic or resilient member and is mounted on a movable contact piece support member such that it can move for swinging or rocking movement; a terminal portion (tab terminal) of the movable contact piece support member is led out to the outside of a box through a corresponding slit formed through the bottom wall of the box; a terminal portion (tab terminal) of a fixed contact piece is led out to the outside of the box through a corresponding slit formed through the bottom wall of the box; an actuator for actuating the movable contact piece is integrally formed on an operation button or knob and extends downwardly therefrom; and when the operation button is operated for rocking operation, the movable contact piece actuator is moved for rocking operation together with the operation button thereby to actuate the movable contact piece so that it is moved to one position where a movable contact mounted thereto is brought into contact with a fixed contact mounted to the fixed contact piece or the other position where the movable contact is spaced apart from the fixed contact.
Rocker switches of this type have been also proposed in the past, and a seesaw switch is disclosed in, for example, Japanese Examined Utility Model Application Publication No. 05-001870 (JP, 05-001870, Y(1993)) published on Jan. 19, 1993, in which a large contact pressure can be applied between a movable contact and a fixed contact. In Japanese Examined Utility Model Application Publication No. 06-035333 (JP, 06-035333, Y(1994)) published on Sep. 14, 1994, there is disclosed a terminal fixing structure for a seesaw switch in which there are no possibility that a bad or poor contact or a joining between contacts by fusion occurs. In Japanese Unexamined Patent Application Publication No. 08-055542 (JP, 08-055542, A(1996)) published on Feb. 27, 1996, there is disclosed a seesaw switch in which if a movable contact and a fixed contact should be joined with each other by fusion, it is ensured that these contacts can be securely opened or released from each other, but a compression coil spring is used as a movable contact actuator. In Japanese Unexamined Patent Application Publication No. 2001-195955 (JP, 2001-195955, A) published on Jul. 19, 2001, a seesaw switch having a dustproof structure is disclosed, but a compression coil spring is used as a movable contact actuator. In Japanese Patent No. 3224949 (JP, 3224949, B) issued on Nov. 5, 2001, there is disclosed a terminal fixing structure of a seesaw switch using a clinching or fastening technique in which a displacement in position of a terminal and/or a displacement in position of a contact is hard to occur when a terminal is fixed by use of a clinching or fastening technique, but a combination or assembly of a torsion coil spring and a movable contact piece is used.
The prior art rocker switches disclosed in the above-stated documents have disadvantages that it is not easy to build or assemble a terminal portion of a movable contact piece support member and a terminal portion of a fixed contact piece in a box and to fix them thereto, and that there sometimes occurs a case that the terminal portion or portions of the movable contact piece support member and/or of the fixed contact piece are securely not fixed to the box. Moreover, there is a drawback that when an operation button is operated, there cannot be obtained actual feeling that the operation button swings lightly and smoothly (without feeling a resistance thereto) as well as that the operation button has positively stopped at its on position or off position, that is, feeling in actuation of the operation button is bad or unfavorable.
In addition, there is a problem in that a movable contact piece is rapidly swung, and since a stable reverse operation thereof cannot be obtained, it is difficult to reduce a bounce time in throwing the movable contact piece to its on position. Furthermore, it is also difficult to make smaller an arc that occurs when the movable contact piece is thrown to its off position.
It is necessary to prevent a trouble or accident that a displacement in position of a movable contact piece occurs or a movable contact piece gets out of place due to an external shock from occurring. However, in the prior art rocker switches disclosed in the above-stated documents, there is not provided means for preventing such trouble or accident from occurring without fail.
Moreover, since it is impossible to prevent an arc that occurs between a movable contact piece and a movable contact piece support member due to a bounce of the movable contact piece in turning a rocker switch on or off, there is a defect that a lifetime of the switch is shortened.
Further, TAB 187 terminal of IEC (International Electrotechnical Commission) standard is used as a terminal portion (tab terminal) of a rocker switch of rated current 10A type, and it is necessary that TAB 250 terminal of IEC standard is used as a terminal portion (tab terminal) of a rocker switch of rated current 16A type. The width of TAB 187 terminal is 4.75 mm, while the width of TAB 250 terminal is 6.35 mm. Therefore, the width of TAB 250 terminal is wider by 1.6 mm than that of TAB 187 terminal. For example, in some machine or apparatus having a rocker switch of rated current 10A type mounted thereon, if the user therefor wishes to use a rocker switch of rated current 16A type in place of the rocker switch of rated current 10A type, the machine or apparatus must have a space in which the rocker switch of rated current 16A type can be accommodated at a location that the rocker switch of rated current 10A type has been now mounted, because the external sizes (width and depth) of a box of the rocker switch of rated current 16A type are necessarily larger than those of a box of the rocker switch of rated current 10A type. If the machine or apparatus should not have a space in which a rocker switch having its external width and depth larger than those of the rocker switch of rated current 10A type can be accommodated, it is impossible to use the rocker switch of rated current 16A type in that machine or apparatus.
In recent years, various kinds of OA machines or equipments, amusement and game machines, measurement instruments, medical instruments and the like are showing a tendency to be miniaturized more and more, and hence there is a strong demand for the advent of a miniature rocker switch that has larger rated current/voltage value as well as can be accommodated in a small space.
An object of the present invention is to provide a rocker switch in which components thereof can easily be built or assembled in a box and fixed thereto, and yet, a rapid reverse operation as well as favorable and excellent feeling in actuation of an operation button when it is operated, can be obtained.
Another object of the present invention is to provide a rocker switch in which favorable and excellent feeling in actuation of an operation button when it is operated, can be obtained, and yet, there occurs no trouble or accident that a displacement in position of a movable contact piece occurs or a movable contact piece gets out of place due to an external shock.
Another object of the present invention is to provide a rocker switch in which favorable and excellent feeling in actuation of an operation button when it is operated, can be obtained, and yet, no arc occurs at all between a movable contact piece and a movable contact piece support member due to a bounce of the movable contact piece.
Still another object of the present invention is to provide a rocker switch of a predetermined rated current/voltage that can be used as another rocker switch of rated current/voltage larger than the predetermined rated current/voltage without increasing the external sizes thereof.
In order to accomplish the foregoing objects, in one aspect of the present invention, there is provided a rocker switch comprising: a movable contact piece having a generally U-like shape, that is made of an elastic member; a movable contact that is mounted on a portion of the movable contact piece near one end thereof; a movable contact piece support member that comprises: a movable contact piece support for swingably supporting the movable contact piece; and a tab terminal hanging down from the movable contact piece support; a pair of detents that is formed to project on the both side edges of the tab terminal of the movable contact piece support member in the direction of the width of the tab terminal at predetermined positions thereof; a fixed contact piece that comprises: a fixed contact support on which a fixed contact is mounted; and a tab terminal hanging down from the fixed contact support; a pair of detents that is formed to project on the both side edges of the tab terminal of the fixed contact piece in the direction of the width of the tab terminal at predetermined positions thereof; a box that has its top opened and a slit formed through the bottom wall of the box, through which the tab terminal of the movable contact piece support member is pulled out toward the outside and a slit formed through the bottom wall of the box, through which the tab terminal of the fixed contact piece is pulled out toward the outside; an operation button that comprises a movable contact piece actuator to be engaged with the movable contact piece and is swingably mounted to the opening portion of the box; and a recess that is formed on a portion of the movable contact piece near the other end thereof to extend in the direction of the width of the movable contact piece and has a generally circular arc-shape in section engaged with a generally circular arc-shaped tip in section of the movable contact piece actuator of the operation button, and wherein the movable contact piece support member is engaged and secured on the bottom wall of the box by forcedly bending a pair of the detent pieces of the tab terminal thereof outwardly in the direction of the width thereof and engaging them, the tab terminal being pulled out toward the outside through the corresponding slit formed through the bottom wall of the box; the fixed contact piece is engaged and secured on the bottom wall of the box by forcedly bending a pair of the detent pieces of the tab terminal thereof outwardly in the direction of the width thereof and engaging them, the tab terminal being pulled out toward the outside through the corresponding slit formed through the bottom wall of the box; the operation button is swingably mounted to the opening portion of the box in the state that the generally circular arc-shaped tip in section of the movable contact piece actuator is engaged with the recess of a generally circular arc-shape in section of the movable contact piece; and the movable contact piece actuator that is swingable with the swinging movement of the operation button causes the movable contact piece to be swung to the switch-on position where the movable contact thereof comes into contact with the fixed contact or the switch-off position where the movable contact thereof is away from the fixed contact.
In a first preferred embodiment, the operation button further includes a rod-like member projecting beyond the tip of the movable contact piece actuator. The movable contact piece has an elongate aperture at a portion thereof near the recess, into which the forward end of the rod-like member of the operation button is inserted with a clearance or play therebetween. The forward end of the rod-like member is inserted into the elongate aperture with a clearance or play therebetween when the operation button is swingably mounted to the opening portion of the box.
In a second preferred embodiment, the box has a generally rectangular or square shape in plan, and a partition wall that isolates the tab terminal of the movable contact piece support member and the tab terminal of the fixed contact piece from each other, is formed on the bottom surface of the bottom wall of the box. The length of the partition wall is set to be substantially equal to those of the tab terminals, and the slits are formed obliquely in the bottom wall of the box from the vicinities of the corners thereof to form a predetermined angle with one side of the bottom wall respectively.
In a third preferred embodiment, the rocker switch further includes a conductive resilient piece that is swingably mounted on the movable contact piece support member. The conductive resilient piece is located, when the movable contact piece is swingably mounted on the movable contact piece support member, between the movable contact piece and the movable contact piece support member and is in electrically contact with both the movable contact piece support member and the movable contact piece.
The conductive resilient piece comprises: a sheet-like resilient piece body; a pair of opposed retentive pieces that substantially stand erect from the resilient piece body; and at least one pair of opposed protrusions that project outwardly and upwardly from the resilient piece body in the direction of forming generally right angles with a line connecting the retentive pieces. A pair of the retentive pieces is pressed and abutted against the movable contact piece support member when the movable contact piece is swingably mounted on the movable contact piece support member, and at least one pair of the protrusions is pressed and abutted against the movable contact piece when the movable contact piece is swingably mounted on the movable contact piece support member through the resilient piece therebetween.
With the construction described above, it is possible to mount or assemble the fixed contact piece and the movable contact piece support member in the box and to secure them simply and easily with accuracy and stability. In addition, engagement between each movable contact piece actuator of the operation button and the movable contact piece is in the rolling friction state. As a result, there can be obtained actual feeling that the operation button swings lightly and smoothly as well as that the operation button has positively stopped at its switch-on position or switch-off position, and feeling in actuation of the operation button comes to much favorable or excellent. Furthermore, the quick swinging operation of the movable contact piece is made possible and the more stable reverse operation of the movable contact pieces is obtained. Accordingly, a bounce time in throwing the movable contact piece to its switch-on position can be much more reduced and an arc occurring in throwing the movable contact piece to its switch-off position can also be made smaller. As a result, wear and tear of the contacts are further restrained and there can be provided the contacts the lifetime of which is much more longer.
In addition, in accordance with the first embodiment, since the rod-like member of the movable contact piece actuator of the operation button is inserted into the elongate aperture of the movable contact pieces with a clearance between the rod-like member and the periphery of the elongate aperture, it is ensured that there occurs no trouble or accident that a displacement in position of the movable contact piece occurs or the movable contact piece falls off due to an external shock, and hence it is possible to make the operation of the rocker switch stable.
In accordance with the second embodiment, since a rocker switch of a predetermined rated current/voltage can be used as another rocker switch of rated current/voltage larger than the predetermined rated current/voltage without increasing the external sizes of the box, OA machines or equipments, amusement and game machines, measurement instruments, medical instruments and the like, for example, can be modified to ones each having larger rated current/voltage value without increasing sizes thereof.
In accordance with the third embodiment, since no arc occurs between the movable contact piece and the movable contact piece support piece due to a bounce occurring on turning the rocker switch on or off, a lifetime of these components are greatly lengthened.